Wednesday night on ABC a new drama debuted. "Designated Survivor" explores what might happen if calamity strikes the capitol. Kiefer Sutherland stars as a little-known cabinet secretary who, in an instant, becomes Commander in Chief.

The scenario is not fiction; it's one government officials actually train for. Those who have been the designated survivor described it as a frightening but also reassuring experience. They said Secret Service and military aides take it very seriously, even if they found it hard to believe that they were just one calamity away from becoming President of the United States.

"I was absolutely shocked and somewhat upset that I was going to become the designated survivor," said Tommy Thompson, former governor of Wisconsin and cabinet secretary.

While President George W. Bush addressed a joint session of Congress, Thompson was holed up in a secret government facility.

"The concerns were so much more magnified that evening. Our whole government, Supreme Court is in one building. What could happen?" Thompson said.

"It was in a mountain and it had all the capacity in order to run government from there. They wanted to make sure if that a terrible tragedy were to happen, government would continue. Vice President Cheney was almost anal about C.O.G. - continuity of government - so from 9/11 until January, several secretaries - at least one or two - had to spend the weekend out at this location where I was at," he said.

Only later did Thompson learn he wasn't the only designated survivor that night; Vice President Cheney also spent the evening in a secret bunker.

On television, "Designated Survivor" illustrated the tension of a terror-fueled turnover of power. Former commerce secretary and White House Chief of Staff Bill Daley said it's something people in government drill for.

"All the agencies that were there had worked through this scenario themselves so they were prepared. And then I'm the guy who walks in with no knowledge of anything and they're like, 'Ok, Mr. President, what do you want to do?' And I'm like, 'Okay! What do you think?'" Daley said.

Daley was the designated survivor during Bill Clinton's 1998 State of the Union Address. While Clinton talked, Daley dined with his brother, some friends and a small army of newly reinforced Secret Service agents.

When word came that the speech was over and the president was safely back at the White House, Daley said 'his' security vanished.

"The cars leave and I have to get a cab and go home!" Daley said.

As for not becoming president that night, he felt good about it.

"Thank god! Probably for the country. Thank god in a lot of ways for the country!" he said.

The idea of having a designated survivor originated during the Cold War when there were concerns about a nuclear strike. They're selected by the White House Chief of Staff and are typically lower level cabinet members; someone whose absence wouldn't generally be noticed.